Exchange and Transport

Question 1

what is the need for specialised exchange surfaces

Answer 1

• take in products for metabolic reactions
• excrete waste products of metabolic reactions

Question 2

why is diffusion slow in multicellular organisms

Answer 2

• cells are deep within the body
• large animals have a low surface area: volume ratio
• higher metabolic rate so use products faster

Question 3

what are specialised features of multicellular organisms

Answer 3

• large surface area
• good blood supply
• good ventilation

Question 4

how do root hair cells have a large surface area

Answer 4

• each branch has millions of microscopic hairs
• gives large surface area to increase the rate of water and mineral absorption from the soil

Question 5

how do alveoli have a large surface area

Answer 5

• each alveolus is made from a thin alveolar epithelium
• oxygen diffuses out into the blood
• carbon dioxide diffuses in the opposite direction
• thin alveolar epithelium decreases the distance that oxygen and carbon dioxide diffusion take place

Question 6

what is cartilage

Answer 6

• has tracheal rings
• support trachea and bronchi to prevent it from collapsing

Question 7

what is ciliated epithelium

Answer 7

• along the trachea down to the bronchi
• sweep mucus, dust, bacteria upwards and away from the lungs
• prevents lung infections

Question 8

what are goblet cells

Answer 8

• scattered throughout the cilia
• secrete mucus that traps dust, microorganisms and bacteria from reaching the lungs
• swallowed and destroyed by stomach acid

Question 9

what is squamous epithelium

Answer 9

• forms alveolar wall and is very thin
• permeable for easy diffusion of gases

Question 10

what is smooth muscle

Answer 10

• walls of bronchi and bronchioles
• regulate the flow of air into the lungs by dilating when more air is needed and constricting when less air is needed

Question 11

What are elastic fibres

Answer 11

• enable the lungs to stretch and recoil

Question 12

what is the nasal cavity

Answer 12

• large surface area with a good blood supply
• hairy lining to secrete mucus
• moist surfaces reducing evaporation

Question 13

what is the trachea

Answer 13

• carries clean warm air from the nose into the chest
• supported by cartilage to help move food
• lined with ciliated epithelium and goblet cells

Question 14

what is the bronchus

Answer 14

• trachea divides to form left bronchus going to the left lung
• forms right bronchus going to the right lung
• supported by cartilage

Question 15

what are bronchioles

Answer 15

• bronchi divide to form small bronchioles
• small bronchioles have no cartilage
• smooth muscle contracts bronchioles constrict
• smooth muscle relaxed bronchioles dilate

Question 16

what are alveoli

Answer 16

• small air sacs
• flattened epithelial cells, collagen, elastic fibres
• elastic recoil - alveoli stretches when air is drawn in and squeeze air out when resting

Question 17

what are the adaptations of alveoli

Answer 17

• large surface area
• thin layers for a short diffusion distance
• good blood supply - maintain carbon dioxide and oxygen concentration
• good ventilation

Question 18

what is the process of inspiration

Answer 18

• external intercoastal and diaphragm muscles contract
• ribcage moves upwards and downwards
• diaphragm flattens increasing volume in the thorax
• lung pressure decreases
• air flows into the lungs
• active process so requires energy

Question 19

what is the process of expiration

Answer 19

• external intercoastal and diaphragm muscles relax
• ribcage moves downwards and inwards
• diaphragm curved again
• thorax volume decreases, air pressure increases
• air is forced out of the lungs
• passive process - no energy needed- but can be forced

Question 20

what is a spirometer

Answer 20

• person breathes in and out and the lid of the chamber moves up and down
• movement recorded by a pen attached to the lid of the chamber creating a trace
• soda lime in the tube absorbs carbon dioxide

Question 21

what is tidal volume -

Answer 21

• volume of air that moves into and out of the lungs with each breath

Question 22

what is vital capacity

Answer 22

• volume of air that can be breathed in or out

Question 23

what is the inspiratory reserve volume

Answer 23

• maximum volume of air you can breathe in

Question 24

what is the expiratory reserve volume

Answer 24

• extra amount of air you can force out of your lungs

Question 25

what is residual volume

Answer 25

• extra amount of air you can force out of your lungs

Question 26

what is total lung capacity -

Answer 26

• sum of vital capacity and the residual volume

Question 27

what is breathing rate

Answer 27

• number of breaths taken per minute

Question 28

what is ventilation rate

Answer 28

• total volume of air inhaled in one minute

Question 29

how do you calculate ventilation rate

Answer 29

tidal volume x breathing rate

Question 30

how do fish exchange gases

Answer 30

• water containing oxygen enters through the mouth and passes out through the gills
• gills made of primary lamellae giving a big surface area
• gill filaments covered in secondary lamellae giving a large surface area
• gill plates have lots of blood capillaries and a thin surface layer of cells to speed up diffusion
• blood flows through the gill plates in one direction and water in the other - counter current system

Question 31

how do fish carry out ventilation

Answer 31

• opens mouth and buccal cavity lowered to the floor
• volume of buccal cavity increases decreasing pressure
• water is sucked into the cavity
• volume decreases and pressure increases
• water is forced out of the cavity across the gill filaments
• each gill is covered by a bony flap (operculum)
• when pressure is increased the operculum on both sides is forced open allowing water to leave the gills

Question 32

how do insects exchange gases

Answer 32

• air moves into the trachea through spiracles
• oxygen travels down the concentration gradient towards the cells
• carbon dioxide moves towards spiracles to be released in the atmosphere
• trachea branches into tracheoles that have thin permeable walls - fluid where oxygen can dissolve
• oxygen diffuses from the fluid to body cells
• carbon dioxide diffuses in the opposite direction